Self-sealing tube fittings of various types are known in the art. Such fittings enable circuits and machinery to stay under pressure when being checked and maintained. To make a connection, the end of a tube is inserted into the fitting. As the tube is inserted, the end of the tube pushes against a valve to open the valve and establish fluid communication between the tube and a flow passage in the fitting. Withdrawal of the tube from the fitting is prevented by a collet that grips the tube when the collet is urged outwardly against a cam surface. To remove the tube, the collet is pushed inwardly to release the tube so that it can be withdrawn from the fitting. As the tube is withdrawn, a spring causes the valve to close to prevent the escape of pressurized fluid from the fitting.
In order to satisfy more demanding performance characteristics, some self-sealing fittings could only be used with rigid tubes. If a flexible tube was desired or needed, the prior art solution was to equip the flexible tube with a male fitting for insertion into a female coupling.